In a gas turbine engine, pressurized air is provided from the compressor stage to the combustor, whereupon it is mixed with fuel and is burned in the combustion chamber. The amount of pressurized air that enters the fuel/air mixers, and correspondingly the inner and outer passages of the combustor, has typically been regulated by inner and outer cowls located upstream of the fuel/air mixers and the combustor dome. Such cowls have been generally held in place by means of a bolted joint that includes the combustor dome, the cowl, and either the inner or outer combustor liner. Accordingly, both the outer and inner cowls of a gas turbine engine experience a slight change in pressure thereacross, as well as a vibratory load induced by the engine. While these environmental factors have a greater effect on the outer cowl, they nevertheless cause wear on both cowls and consequently limit the life thereof.
In addressing this problem, the prior art has generally taken one of the following approaches. The first of which involves use of a sheet metal body for the cowls with a lip formed at the leading edge thereof, preferably by curling or wrapping the sheet metal around a damper wire. However, it has been found that this design is life-limited due to a rubbing-type wear occurring at the interface of the wire and the sheet metal body caused by a thermal mismatch between the wire and the wrap. More specifically, the thermal mismatch causes the sheet metal to unwrap around the wire, creating a gap between the wire and the cowl. In addition, white noise exiting the diffuser and/or combustor acoustics creates high cycle fatigue vibratory loading of the wire against the sheet metal wrap. Thus, the combined rubbing and vibratory induced shaking of the wire against the metal wrap result in the wrapped portion of the cowl thinning, cracking and eventually liberating sheet metal and wire fragments.
Another cowl design involves a machined ring that forms the leading edge lip of the cowl, where the ring is welded to a formed sheet metal body. Such a machined ring provides a solid lip for the cowl, which is desirable, but circumferential welding thereof to the formed sheet metal body has resulted in stress concentrations both in and around the weld.
A one-piece cowl design is disclosed in a U.S. patent application entitled xe2x80x9cOne-Piece Combustor Cowl,xe2x80x9d U.S. Pat. No. 5,924,288, which discloses a cowl that is casted with a solid lip of increased thickness at a leading edge thereof. While suitable for its intended purpose, this cowl tends to be both heavier and more costly than a sheet metal cowl.
The above discussed and other drawbacks and deficiencies are overcome or alleviated by a corrugated cowl. In an exemplary embodiment of the invention, a cowl for use with a combustor of a gas turbine engine, the cowl includes a main body with an annular corrugation. In another exemplary embodiment a combustor of a gas turbine engine, the combustor includes: a hollow body defining a combustion chamber, the hollow body having a liner; an outer cowl having an annular corrugation, the cowl connecting to the liner; and an inner cowl connecting to the liner. A method of configuring a cowl for a gas turbine engine combustor, the method includes forming an annular corrugation in a main body of the cowl.